Low pressure pilot operated relief valve

ABSTRACT

Embodiments of the invention provide a relief valve body arranged for connecting to a pressure vessel. The relief valve body includes an inlet configured to connect to a pressure vessel and an integrated nozzle downstream from the inlet and extending along an axis. The integrated nozzle includes a nozzle exterior surface, a nozzle bulb, and a valve seat and defines a nozzle expansion region. The relief valve body further includes a redirecting pallet, a valve interior surface having at least one ramped portion downstream from the integrated nozzle and redirecting pallet, and an outlet downstream from the at least one ramped portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S patent applicationSer. No. 14/600,943, filed on Jan. 30, 2015, and entitled “Low PressurePilot Operated Relief Valve”, which claims the benefit of United StatesProvisional Application No. 61/928,850 filed on Jan. 17, 2014, theentire disclosures of which are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates generally to relief valves for pressurevessels and, in particular, to pilot operated relief valves.

Current manufacturers commonly employ valve body designs intended todirect a fluid flow at a right angle with respect to an inlet withoutconsideration to an expansion of the traversing fluid. Additionally,such designs typically do not provide means for controlling theexpansion of the traversing fluid, and commonly rely solely on acylindrical curtain area to allow the traversing fluid to pass into thevalve body. Such valves deliver inferior flow rate efficiency throughthe valve body and, therefore, it would be desirable to have a valvebody that provides a means to control the expansion of the traversingfluid through the valve body.

BRIEF SUMMARY OF THE INVENTION

The aforementioned shortcomings can be overcome by providing a reliefvalve body that includes features configured for increased efficiency offluid flowing through the valve. Additionally, an interior shape of theinventive relief valve body allows for controlled expansion of the fluidand the management of the fluid energy in assisting in the change ofdirection of fluid flow. Such features may also provide advantages toapplications employing any system, device, or structure wherein a fluidflow direction is changed in a controllable manner between an inlet andan outlet.

In one aspect, the invention provides a relief valve body arranged forconnecting to a pressure vessel. The relief valve body includes an inletconfigured to connect to a pressure vessel and an integrated nozzledownstream from the inlet and extending along an axis. The integratednozzle includes a nozzle exterior surface, a nozzle bulb, and a valveseat and defines a nozzle expansion region. The relief valve bodyfurther includes a redirecting pallet, a valve interior surface havingat least one ramped portion downstream from the integrated nozzle andredirecting pallet, and an outlet downstream from the at least oneramped portion.

In another aspect, the invention provides a relief valve body arrangedbetween an inlet and an outlet. The relief valve body includes anexpanding nozzle extending along an axis, a first ramp extending in anarcuate path from an apex to a first terminating point, and a secondramp extending in an arcuate path from the apex to a second terminalpoint. The first ramp and the second ramp define an expanding flow areafor a fluid flow between the inlet and the outlet.

In another aspect, the invention provides a relief valve body arrangedfor connecting to a pressure vessel. The relief valve body includes aninlet for connecting to a pressure vessel and an integrated nozzledownstream from the inlet and extending along an axis. The integratednozzle defines a nozzle expansion region and includes a nozzle exteriorsurface, a nozzle bulb defining a substantially protrudent shape thatprotrudes away from the axis, and a valve seat. The relief valve bodyfurther includes a valve interior surface having a first ramped portion,a second ramped portion, a flat portion, and an arced portion. The firstramped portion expands a fluid flow area by ramping from a ramp apexaround the integrated nozzle to the flat portion. The second rampedportion expands the fluid flow area by ramping from the ramp apex aroundthe integrated nozzle to the flat portion on an opposite side of theintegrated nozzle from the first ramped portion. The relief valve bodyfurther includes a redirecting pallet defining a curved portion and aflat portion that cooperate to direct a fluid flow towards the valveinterior surface and an outlet downstream from the first ramped portionand the second ramped portion.

The foregoing and other aspects and advantages of the invention willappear from the following description. In the description, reference ismade to the accompanying drawings which form a part hereof, and in whichthere is shown by way of illustration a preferred embodiment of theinvention. Such embodiment does not necessarily represent the full scopeof the invention however, and reference is made therefore to the claimsand herein for interpreting the scope of the invention.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood and features, aspects andadvantages other than those set forth above will become apparent whenconsideration is given to the following detailed description thereof.Such detailed description makes reference to the following drawings.

FIG. 1 is a cross-sectional side view of a relief valve body inaccordance with the present invention.

FIG. 2 is a perspective, bottom view of the relief valve body of FIG. 1.

FIG. 3 is a perspective, top view of the relief valve body of FIG. 1with a quarter cutout and the redirecting pallet removed.

FIG. 4 is a perspective, bottom view of an example relief valve with aquarter cutout.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

The present invention introduces a relief valve body 100 designed foruse in any applications employing systems or components designed formaintaining fluid flows, such as, for example, systems, vessels ortankers used for processing, transporting or storing liquefied naturalgas (LNG). Features of the relief valve body 100 in accordance with thepresent invention will be readily apparent and are generally indicatedin FIGS. 1-4.

As shown in FIG. 1, the relief valve body 100 is configured tocontrollably divert a fluid flow between an inlet 102 and an outlet 104.The inlet 102 is arranged at an angle of approximately 90 degrees withrespect to the outlet 104. In other embodiments, the inlet 102 may bearranged at a different angle with respect to the outlet 104, asdesired. The inlet 102 and the outlet 104 of the relief valve body 100can be designed with capabilities and/or components for coupling to afluid-bearing vessel, device, or system. In the illustrated embodiment,the inlet 102 includes an inlet mounting feature 103 in the form of aflange and the outlet 104 includes an outlet mounting feature 105 in theform of a flange. In other embodiments, the inlet mounting feature 103and/or the outlet mounting feature 105 may be in the form of a threadedpipe fitting or be arranged differently, as desired.

The relief valve body 100 includes an integrated nozzle 106 downstreamfrom the inlet 102 and extending along an axis 108, a redirecting pallet110, and a valve interior surface 111 arranged downstream from theintegrated nozzle 106 and the redirecting pallet 110. The integratednozzle 106 includes a nozzle exterior surface 112, a nozzle bulb 114,and a valve seat 116 configured to couple to a valve element (not shown)of a pressure relief valve system. The integrated nozzle 106 defines anozzle expansion region 117 generally bounded between plane A and planeB and indicated as element 117. The nozzle expansion region can beshaped and dimensioned to enable a controlled expansion of the fluidflow from the inlet 102 and through the integrated nozzle 106 generallyalong the axis 108. In the illustrated embodiment, the nozzle expansionregion 117 includes a tapered portion generally bounded between plane Band plane C and indicated as element 118 that defines a substantiallyfrusto-conical, or sloped shape and a nozzle exit portion 120,downstream from the tapered portion 118, generally bounded between planeA and plane C and indicated by element 120.

The expansion of the fluid flow traversing the nozzle expansion region117 of the integrated nozzle 106 may be controlled by an expansion ratioR_(exp) defined by the tapered portion 118. In the illustratedembodiment, the expansion ratio R_(exp) of the tapered portion 118 isapproximately 1.8. In other embodiments, the tapered portion 118 candefine a different expansion ratio R_(exp), as desired. For example, theexpansion ratio R_(exp) may be between about 1.7 and 1.9, or in otherembodiments, the expansion ratio R_(exp) may be between about 1.5 and2.1. The shape of the integrated nozzle 106 allows for better control ofexpansion and a standing shock wave of a fluid. As such, the reliefvalve body 100 may be suitable for high pressure flow conditions.

The nozzle exterior surface 112 defines a generally cylindrical shapeand is configured to be downstream from the nozzle bulb 114. The nozzlebulb 114 defines a substantially arced, or protrudent shape that isconfigured to control a standing shock wave of the fluid flow as thefluid flow is being directed towards the valve interior surface 111. Theprotrudent shape of the nozzle bulb 114 protrudes away from the axis108.

With continued reference to FIG. 1, the redirecting pallet 110 isconfigured to receive the fluid flow generally directed along the axis108 from the inlet 102, and divert the fluid flow in directionsgenerally away from the axis 108 and towards the valve interior surface111. The redirecting pallet 110 can be designed to be substantiallycircular, although other shapes are possible. The redirecting pallet 110defines a curved portion 121 and a flat portion 122 that cooperate todirect the fluid flow and develop a more laminar flow profile.

The shape of the redirecting pallet 110, the nozzle bulb 114, and thenozzle expansion region 117 are designed to cooperate and allow forcontrol of the fluid flow as it flows through and away from theintegrated nozzle 106. For example, for higher pressure applications,the nozzle bulb 114 of the integrated nozzle 106 may be shaped to bemore bulbous, or protrude further from the axis 108 than shown in FIG.1, which would allow for a standing shock of the fluid flow to occurprior to entering the valve interior surface 111. In contrast, for lowerpressure applications, the nozzle bulb 114 of the integrated nozzle 106may be shaped to be less bulbous, or protrude less from the axis 108than shown in FIG. 1, which may allow for a more free fluid expansioninto the valve interior surface 111.

With reference to FIGS. 1-3, the valve interior surface 111 includes afirst ramped portion 124, a second ramped portion 126, an arced portion128, and a flat portion 130. The first ramped portion 124 begins at aramp apex 132 and expands a fluid flow area for the fluid flow travelingalong the first ramped portion 124 by ramping towards the outlet 104 andaround the integrated nozzle 106. The fluid flow area continuesexpanding until the first ramped portion 124 engages the flat portion130, as shown in FIG. 1 by the dashed lines illustrating the firstramped portion 124 and the flat portion 130. The second ramped portion126 begins at the ramp apex 132 and expands a fluid flow area for thefluid flow traveling along the second ramped portion 126 by rampingtowards the outlet 104 and around the integrated nozzle 106, in anopposite direction from the first ramped portion 124. The fluid flowarea continues expanding until the second ramped portion 126 engages theflat portion 130. In the illustrated embodiment, the first rampedportion 124 and the second ramped portion 126 engage the flat portion130 in a plane closer to the outlet 104 than the axis 108. In otherembodiments, the first ramped portion 124 and the second ramped portion126 may engage the flat portion 130 in a plane substantially furtheraway, substantially closer to the outlet 104 than the axis 108, or in aplane intersecting the axis 108.

The arced portion 128 defines a gradually decreasing flow area for thefluid flow traveling towards the outlet 104 of the valve body 100. Thegradual decrease in fluid flow area provides a reduced pressure dropbetween the inlet 102 and the outlet 104 of the valve body 100.

The expanded flow area provided by the first ramped portion 124 and thesecond ramped portion 126 provide a reduction in a velocity of the fluidflow traversing from the inlet 102 to the outlet 104 of the relief valvebody 100. This reduction in flow velocity aids in reducing a pressuredrop between the inlet 102 and the 104. Additionally, the reducedvelocity of the fluid flow reduces the Reynolds number of the fluid flowand, therefore, reduces the chance of fluid separation, or turbulence,occurring downstream from the integrated nozzle 106. Thus, the firstramped portion 124, the second ramped portion 126, the arced portion128, and the flat surface 130 enable a superior flow rate efficiency andretain a total pressure of the fluid flow by minimizing a pressure dropbetween the inlet 102 and the outlet 104 of the valve body 100.

FIG. 4 illustrates a use for the relief valve body 100 described above.The relief valve body 100 may be integrated into a pilot operated reliefvalve 200, which as known in the art, is used to provide gradual,proportional or pre-set pressure relief. The pilot operated relief valve200 shown in FIG. 4 includes pilot valves 202, a guide 204, a guide pin206, and a diaphragm 208 adjacent to the redirecting pallet 110. Anupper blousing plate 210 and a lower blousing plate 212 are locatedadjacent to the diaphragm 208. The pilot valves 202 are mounted on acover 214 that is coupled to the valve body 100 and encloses the valveinterior surface 111 and the diaphragm 208.

Although not shown, the pilot operated relief valve 200 also includes avalve element removably coupled to the valve seat 116 of the integratednozzle 106. The valve element is typically formed from a flexiblematerial and can be attached to a bottom surface of the redirectingpallet 110. The valve element may include a valve element cover that canbe formed from a polytetrafluoroethylene (PTFE) material, which laysover the valve element, serving as a protective layer.

Operation of the pilot operated relief valve 200 including the reliefvalve body 100 will be described with reference to FIG. 4. The valveelement (not shown for clarity in describing the features of the reliefvalve body 100) is typically biased towards a first position where fluidflow is prevented from the inlet 102 to the outlet 104 of the reliefvalve body 100. Once a predetermined pressure is detected by the pilotvalves 202, the valve element is allowed to move from the first positionto a second position where fluid flow is allowed between the inlet 102and the outlet 104 of the relief valve body 100. The fluid flowtraveling from the inlet 102 to the outlet 104 is first expanded in thenozzle expansion region 117 downstream from the inlet 102. The fluidflow then exits the integrated nozzle 106 through the nozzle exit region120 and is directed towards the valve interior surface 111 by theredirecting pallet 110. The first ramped portion 124 and the secondramped portion 126 then expand the fluid flow and direct the fluid flowtowards the outlet 104 in an efficient manner.

The design of a relief valve body 100, in accordance with the presentinvention, is focused on delivering superior flow rate efficiencythrough the valve interior surface 111 of the valve body 100, forexample, in the case of subsonic fluid flow. The expansioncharacteristics of the fluid flow are tightly controlled throughgeometrical configurations of the integrated nozzle 106 features, theredirecting pallet 110 shape, and the design of the portions 124, 126,128, and 130 of the interior valve surface 111. The controlled expansionof a gas, for example, minimizes losses and retains a total pressure asmuch as possible until the outlet 104 of the valve body 100.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein.

We claim:
 1. A relief valve body arranged for connecting to a pressurevessel, the relief valve body comprising: an inlet configured to connectto a pressure vessel; an integrated nozzle downstream from the inlet andextending along an axis, the integrated nozzle including a nozzleexterior surface, a nozzle bulb, and a valve seat and defining a nozzleexpansion region; a redirecting pallet; a valve interior surfaceincluding at least one ramped portion downstream from the integratednozzle and redirecting pallet; an outlet downstream from the at leastone ramped portion wherein the redirecting pallet defines a curvedportion and a flat portion that cooperate to direct a fluid flow towardsthe valve interior surface; and wherein the valve interior surfacefurther includes an arced portion and a flat portion both connected tothe outlet.
 2. The relief valve body of claim 1, wherein the nozzleexpansion region defines an expansion ratio R_(exp) of approximately1.8.
 3. The relief valve body of claim 1, wherein the nozzle expansionregion defines an expansion ratio R_(exp) of between about 1.5 and about2.1.
 4. The relief valve body of claim 1, wherein the nozzle expansionregion defines a substantially frusto-conical shape.
 5. The relief valvebody of claim 1, wherein the nozzle bulb defines a substantiallyprotrudent shape that protrudes away from the axis.
 6. The relief valvebody of claim 1, wherein at least one ramped portion includes a firstramped portion and a second ramped portion.
 7. The relief valve body ofclaim 6, wherein the first ramped portion begins at a ramp apex andexpands a fluid flow area by ramping towards the outlet and around theintegrated nozzle, and the second ramped portion begins at the ramp apexand expands the fluid flow area by ramping towards the outlet and aroundthe integrated nozzle in an opposite direction from the first rampedportion.
 8. The relief valve body of claim 7, wherein the first rampedportion and the second ramped portion engage the flat portion in a planebetween the outlet and the axis.
 9. The relief valve body of claim 7,wherein the first ramped portion and the second ramped portion engagethe flat portion in a plane intersecting the axis.
 10. The relief valvebody of claim 7, wherein the first ramped portion and the second rampedportion engage the flat portion in a plane substantially further awayfrom the outlet than the axis.
 11. The relief valve body of claim 7,wherein the arced portion defines a decreasing flow area for a fluidflow traveling towards the outlet.